The present disclosure describes systems and techniques relating to wireless communications by devices that employ more than one wireless communication technology.
Wireless communication devices can use one or more wireless communication technologies, such as code division multiple access (CDMA), orthogonal frequency division multiplexing (OFDM), single carrier frequency division multiple access (SC-FDMA), and time division synchronous code division multiple access (TD-SCDMA). Other examples of wireless technologies include WCDMA (Wideband Code Division Multiple Access), CDMA2000, UMTS (Universal Mobile Telecommunications System), GSM (Global System for Mobile communications), High Speed Packet Access (HSPA), WiMAX (Worldwide Interoperability for Microwave Access), LTE (Long-Term Evolution, often referred to as 4G), WiFi (wireless local area network standards), and Bluetooth (BT). Various examples of wireless communication devices include mobile phones, smartphones, wireless routers, wireless hubs, base stations, and access points. In some cases, wireless communication electronics are integrated with data processing equipment such as laptops, personal digital assistants, and computers.
A wireless device (or the portion of the device that provides end-to-end communications) is often referred to as user equipment (UE) in UMTS and 3GPP LTE. In some wireless networks, each wireless device synchronizes with one or more base stations, such as an evolved Node B (eNB), for wireless communications between the device and the station. In addition to the user data communicated in such networks, network management data is also communicated, which includes both downlink (DL) and uplink (UL) control information. For example, LTE uses uplink control information (UCI) and the hybrid automatic repeat request (HARQ) retransmission protocol.
In HARQ, error correction bits, such as forward error correction (FEC) bits, are included in a data transmission. When a message is received, error detection information can be used to identify success or failure for decoding of the message. The wireless communication device can send an acknowledgement (ACK) or a negative acknowledgement (NACK) based on the success or failure of the decoding. This lets the transmitter of the message know whether the message was received successfully or should be retransmitted. The message can be retransmitted as many times as necessary, but in typical wireless networks there will be a limit placed on the number of attempted retransmissions.
In addition, a typical wireless device will implement two or more wireless technologies and so have radios that need to coexist with each other in the same device. For example, LTE UE may coexist with other radios in a device, which is noted in LTE as in-device coexistence (IDC). Other radios' receiving performance may be significantly degraded by LTE uplink transmission from UE if the operating bands of LTE and the other radios are too close. Examples are the ISM (Industrial Scientific and Medical) band at 2400-2480 MHz (for BT and WiFi) and the LTE band 40 at 2300-2400 MHz. Thus, some coordination between LTE and other radios is desired so the LTE UE can stop transmission while another radio is receiving important information.
Current approaches to such coordination include: (1) the use of guard bands and filtering, such that LTE UE transmission and other radios' reception can happen at the same time; (2) priority-based puncture, where a device controller punctures LTE uplink subframes (i.e., gives up LTE uplink transmission) when there is some critical information that must be received by other radios; (3) scheduled puncture, where a more advanced eNB can inform LTE UE which uplink subframes are not scheduled to transmit information; and (4) random puncture, where a device controller randomly punctures uplink subframes, and allows other radios to receive in these subframes. Further, it has been suggested that coexistence of wireless technologies, such as LTE with BT, would benefit from alignment of subframe and slot boundaries of the respective wireless technologies.